src/hiero_sdk_python/query/fee_estimate_query.py (1)

48-60: ⚠️ Potential issue | 🔴 Critical

Use the actual Client REST/retry API here.

The concrete client exposes network.get_mirror_rest_url() and max_attempts, not mirror_network / max_retries. With a real Client, Line 48 raises AttributeError, and the retry loop ignores the caller’s configured attempt budget.

🐛 Suggested fix

-        url = f"{client.mirror_network}/api/v1/network/fees?mode={mode.value}"
+        url = f"{client.network.get_mirror_rest_url()}/network/fees?mode={mode.value}"
@@
-        max_retries = getattr(client, "max_retries", 3)
+        max_retries = client.max_attempts

Verify against the actual client/network definitions:

#!/bin/bash
set -euo pipefail
rg -n '\bmirror_network\b|\bmax_retries\b|\bmax_attempts\b|get_mirror_rest_url' \
  src/hiero_sdk_python/query/fee_estimate_query.py \
  src/hiero_sdk_python/client/client.py \
  src/hiero_sdk_python/client/network.py

src/hiero_sdk_python/fees/fee_estimate_response.py (1)

14-14: 🧹 Nitpick | 🔵 Trivial

Consider making total a computed property to enforce the fee formula invariant.

Storing total as a separate field risks drift from node_fee/network_fee/service_fee subtotals. The PR objective specifies a precise formula: total = node_fee + network_fee + service_fee. A computed property would guarantee this invariant.

Note: Since this is a frozen dataclass, you'd need to use __post_init__ validation or convert to a computed property with @property.

src/hiero_sdk_python/query/fee_estimate_query.py (1)

98-100: ⚠️ Potential issue | 🟠 Major

Hardcoded max_retries = 2 ignores the configurable _max_attempts.

The class has self._max_attempts = 10 (line 21) with a setter, but the retry loop uses a hardcoded max_retries = 2. The configuration is effectively ignored.

🐛 Proposed fix

-    max_retries = 2
-    
-    for attempt in range(max_retries):
+    for attempt in range(self._max_attempts):
         try:
             response = requests.post(

Also update line 117:

-            if attempt == max_retries - 1:
+            if attempt == self._max_attempts - 1:

src/hiero_sdk_python/query/fee_estimate_query.py (4)

27-27: ⚠️ Potential issue | 🟠 Major

FeeEstimateQuery still bypasses the Query base class.

Per coding guidelines for src/hiero_sdk_python/query/**/*.py, newly added query subclasses must extend Query directly and delegate execution lifecycle (retries, backoff, _before_execute, node selection) to _Executable; subclasses must not implement custom retry logic or manage deadlines manually. This class is a standalone builder with its own HTTP retry loop, no inheritance from Query, and none of the required abstract methods (_make_request, _get_query_response, _get_method).

While HIP-1261 targets the Mirror Node REST API rather than gRPC, it still needs to integrate with the existing query architecture (e.g., via a Mirror-style query base or a thin adapter that preserves the base lifecycle) so retries/backoff/error propagation remain consistent with the rest of the SDK.

As per coding guidelines: "Ensure they extend Query directly; Verify required abstract methods are implemented; ... Subclasses MUST NOT: Override retry logic ... Manage gRPC deadlines manually".

---

62-62: ⚠️ Potential issue | 🟠 Major

_max_backoff = 0 still disables backoff.

With self._max_backoff = 0, _backoff() computes delay = min(0.5 * 2**attempt, 0) = 0, so retries fire immediately. This defeats the retry policy required by HIP-1261 for UNAVAILABLE / DEADLINE_EXCEEDED and can hammer the Mirror Node.

🐛 Proposed fix

-        self._max_attempts = 10
-        self._max_backoff = 0
+        self._max_attempts = 10
+        self._max_backoff = 8  # seconds

---

147-164: ⚠️ Potential issue | 🟠 Major

Silent b"" fallback still produces invalid requests.

If every serialization path fails, the function returns b"" and execute() posts an empty body, which the Mirror Node will either reject opaquely or produce a meaningless estimate. Raise instead so the caller sees a clear error.

🐛 Proposed fix

         try:
             body = transaction.build_transaction_body()
             return body.SerializeToString() if body else b""
         except Exception as exc:  # pylint: disable=broad-exception-caught
-            logger.warning("All serialization methods failed: %s", exc)
-            return b""
+            raise ValueError(
+                f"Failed to serialize transaction for fee estimation: {exc}"
+            ) from exc

---

196-228: ⚠️ Potential issue | 🟠 Major

Chunked transactions are not aggregated; response can be None.

Two concerns on the execute path:

1. HIP-1261 requires FileAppendTransaction and TopicMessageSubmitTransaction fee estimates to be computed per chunk and summed into a single response. The current implementation serializes the transaction once and posts a single request, so chunk fees are never aggregated. The multi-chunk test (test_topic_message_multiple_chunks) only asserts result is not None, which hides this gap.
2. _post_with_retry can return None (line 194) when its loop exits without success; response.json() on line 208 would then raise AttributeError. Either make _post_with_retry always raise on exhaustion or guard here.